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3 years ago

Why do we believe that most of the mass of the milky way is in the form of dark matter?

Physics

1 answer:

Nataliya [291]3 years ago

7 0

<h2>Answer:</h2>

Dark matter is a type of matter, whose composition is unknown and which corresponds to 80% of the matter in the universe. Its name refers to the fact it does not emit or interact with any type of electromagnetic radiation, being completely transparent throughout the electromagnetic spectrum.

However, it interacts with the known matter through <u>gravity</u>.

In this sense, it is believed that the Milky Way has 90% dark matter and only 10% ordinary matter (known matter). Because, like gravity, dark matter can not be observed directly, however its existence is inferred through the movement of the stars and the cosmic dust within the galaxy.

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What is the amount of heat, in Sl units, necessary to melt 1 lb of ice?

likoan [24]

Answer:

Heat required to melt 1 lb of ice is 151.469 KJ

Explanation:

We have given mass of ice = 1 lb

We know that 1 lb = 0.4535 kg

Latent heat of fusion for ice =334 KJ/kg

Amount if heat for fusion of ice is given by

$Q=mL$ , here m is mass of ice and L is latent heat of fusion

So heat $Q=mL=0.4535\times 334=151.469kj$

So heat required to melt 1 lb of ice is equal to 151.469 KJ

3 0

3 years ago

A person can run 400m in 72 s.. At what speed are they running

rewona [7]

Speed = distance/time
= 400/72
=5.55 m/s

6 0

3 years ago

The 59 converted into binary is _____.<br> How do we convert number to binary?

Viefleur [7K]

Answer:

111011

Explanation:

59/2 = 29, remainder is 1

29/2 = 14, remainder is 1

14/2 = 7, remainder is 0

7/2 = 3, remainder is 1

3/2 = 1, remainder is 1

1/2 = 0, remainder is 1

8 0

2 years ago

A mass m at the end of a spring vibrates with a frequency

Wittaler [7]

Answer:

m = 0.59 kg.

Explanation:

First, we need to find the relation between the frequency and mass on a spring.

The Hooke's law states that

$F = -kx$

And Newton's Second Law also states that

$F = ma = m\frac{d^2x}{dt^2}$

Combining two equations yields

$a = -\frac{k}{m}x$

The term that determines the proportionality between acceleration and position is defined as angular frequency, ω.

$\omega = \sqrt{\frac{k}{m}}$

And given that ω = 2πf

the relation between frequency and mass becomes

$f = \frac{1}{2\pi}\sqrt{\frac{k}{m}}$ .

Let's apply this to the variables in the question.

$0.88 = \frac{1}{2\pi}\sqrt{\frac{k}{m}}\\0.60 = \frac{1}{2\pi}\sqrt{\frac{k}{m+0.68}}\\\frac{0.88}{0.60} = \frac{\frac{1}{2\pi}\sqrt{\frac{k}{m}}}{\frac{1}{2\pi}\sqrt{\frac{k}{m+0.68}}}\\1.4667 = \frac{\sqrt{m+0.68}}{\sqrt{m}}\\2.15m = m + 0.68\\1.15m = 0.68\\m = 0.59~kg$

6 0

2 years ago

If two stars in the sky are separated by twice the angle projected by your index and pinky fingers, then how many degrees are th

quester [9]

Answer:

The answer is 30 degrees.

Explanation:

The angle between the index and pinky fingers is 15 degrees.

Twice this angle is 2×15=30degrees.

7 0

2 years ago